Great idea, but be careful. If not designed to be heated, some ceramic materials are frangible under localized heat and subject to spalling.
Or, if left unattended and it cracks under heat, it could start a fire, especially if you're using it indoors. Not that long ago, I was watching an old video of a ceramic ashtray (which
should tolerate heat) crack open and dump the hot ashes and lit cigarettes onto the table below it. (The point of that particular video was to warn users not to let too much ash and too many cigarettes build up without emptying ashtrays.)
But still, a nice idea if it can take the heat.